Pen-type electrosurgical instrument

ABSTRACT

An electrocautery device is disclosed. In accordance with one aspect of the invention, the electrocautery electrode/tip is provided with a hollow, conductive tube terminating at its distal end in a ball point type tip. Fluid, preferably conductive fluid, is applied to the proximal end of the hollow electrode/tip, and expelled from the distal end thereof during electrocautery. The ball point distal tip allows the distal tip to be directly applied to the tissue and “rolled” or slid along the tissue. This allows the distal tip to be moved across the tissue without dragging or snagging on the tissue. In addition, the conductive fluid expelled from the distal tip further lubricates the distal tip as it moves across the tissue. If conductive fluid is used, the conductive fluid emanating from the electrode/tip conducts the RF electrocautery energy away from the distal tip so that it is primarily the fluid, rather than the distal tip that actually accomplishes the cauterizing of tissue. That is, the fluid serves as a “virtual” electrocautery electrode. Since it is the fluid, rather than the distal tip that cauterizes, coagulates and ablates, no burns or perforations are made to the tissue, reducing the amount of debris at the site. Also, the flow of fluid through the electrode/tip tends to keep the distal tip clean and cool.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/883,178, filed Jul. 1, 2004, now pending, which is a continuation ofU.S. patent application Ser. No. 10/411,921, filed Apr. 11, 2003, nowU.S. Pat. No. 6,764,487, which is a continuation of U.S. patentapplication Ser. No. 09/955,496, filed Sep. 18, 2001, now U.S. Pat. No.6,585,732, which is a continuation of U.S. patent application Ser. No.09/580,228, filed May 26, 2000, now U.S. Pat. No. 6,358,248, which is acontinuation of U.S. patent application Ser. No. 09/236,034, filed Jan.22, 1999, now abandoned, which is a continuation of U.S. patentapplication Ser. No. 08/556,784, filed Nov. 2, 1995, now U.S. Pat. No.5,897,553, which is a continuation-in-part of U.S. patent applicationSer. No. 08/393,082, filed Feb. 22, 1995, now U.S. Pat. No. 6,063,081,which applications are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to the field of medical instruments,and more particularly relates to an electrocautery device.

BACKGROUND OF THE INVENTION

Various types of electrocautery devices for incising and cauterizingbody tissue are known and used in the medical field. Typically, suchdevices include a conductive tip or needle which serves as one electrodein an electrical circuit which is completed via a grounding electrodecoupled to the patient. Incision of tissue is accomplished by applying asource of electrical energy (most commonly, a radio-frequency generator)to the tip. Upon application of the tip to the tissue, a voltagegradient is created, thereby inducing current flow and related heatgeneration at the point of contact. With sufficiently high levels ofelectrical energy, the heat generated is sufficient to cut the tissueand, advantageously, to simultaneously cauterize severed blood vessels.

It is widely recognized in the prior art that the often substantialamount of smoke produced by electrocauterization of tissue is at leastunpleasant, and in some cases distracting or even hazardous to theoperator and other attending medical personnel. As a result, it has beenproposed, and is common, to provide an electrocautery device withsmoke-aspirating capabilities, such that the smoke produced fromelectrocauterization is quickly withdrawn from the area of incision.Smoke aspiration may be accomplished by providing, in the handle of theelectrocautery device near the electrocautery tip/electrode, an inletport to be coupled to a vacuum or suction source. Examples of this aredescribed in U.S. Pat. No. 4,307,720 to Weber, Jr., entitled“Electrocuted Apparatus and Method and Means for Cleaning the Same;” inU.S. Pat. No. 5,242,442 to Hirschfeld, entitled “Smoke AspiratingElectrosurgical Device;” and in U.S. Pat. No. 5,269,781 to Hewell,entitled “Suction Assisted Electrocuted Unit.”

It has also been recognized in the prior art that the accumulation ofcoagulated blood, tissue rubble, and other debris on the electrode/tipof an electrocautery device can present a problem for the operator,necessitating the periodic cleaning of the tip, e.g., by wiping the tipover sterilized gauze or the like. This is generally regarded asundesirable, since the need to clean the electrode/tip tends tointerrupt the incision procedure and increases the risks associated withcontamination of the tip or the incision, damage to the tip, injury tothe operator, and the like. To address this problem, it has beenproposed in the prior art to provide an electrocautery instrument inwhich the electrode/tip is in slidable engagement with the instrument'shandle, such that when the tip is retracted into the hand, any adheringdebris automatically scraped off onto the tip of the handle. Such aninstrument is proposed in the above-referenced Weber, Jr. '720 patent.While this arrangement may have some benefit, it still may be necessaryto wipe off the tip of the handle once the tip is retracted. It isbelieved that a more direct and effective approach to the problem wouldbe to reduce the amount of debris created, during the electrocauteryprocess, thereby eliminating or at least reducing the need to clean theelectrode/tip.

Atrial fibrillation is the condition where the normal rhythmiccontractions of the heart are replaced by rapid irregular twitchings ofthe muscular heart wall. At least 1 million people in the U.S. sufferfrom atrial fibrillation. There are at least three detrimental sideeffects that occur during atrial fibrillation: a rapid irregularheartbeat; impaired cardiac hemodynamics due to a loss of AV synchrony;and an increased vulnerability to thromboembolism. Surgical Treatment ofCardiac Arrhythmias, by Willis Hurst, pg. 867.

The typical treatment for atrial fibrillation has been to give thepatient drugs. For most patients with atrial fibrillation, this therapyhas been only moderately effective and has typically producedundesirable side effects.

In view of the problems with drug therapy to treat atrial fibrillation,it has been recognized as desirable to find a surgical treatment thatwould permanently cure atrial fibrillation. Cardiovascular DeviceUpdate, July 1995, pg. 1. Although radiofrequency catheter ablation(RFCA) has proven to be a safe and effective way of treating the mostbenign causes of supraventricular tachycardia (SVT), such asWolff-Parkinson-White and AV nodal re-entry tachycardia, using ablationto treat atrial fibrillation has proven to be challenging. Id.

The so called “maze” procedure has been developed to treat atrialfibrillation. In the “maze” procedure, incisions are made into the rightand left atria via an open chest surgical procedure. These incisions arelocated to interrupt all the potential re-entry circuit patterns thatcould occur in the atria and cause atrial fibrillation. The clinicalsuccess with the “maze” procedure has been good.

A problem with the “maze” procedure is that it requires open chestsurgery which is undesirable. It has been recognized that it would bedesirable to duplicate the “maze” procedure with ablation. Id. at pg. 3.This would allow the possibility of performing a “maze”-like procedurethorascopically. However, it has also been recognized that currentablation technology has not developed to allow the “maze” procedure tobe duplicated with ablation. Id.

A problem with prior art ablation has been that the ablating tip, ifleft in contact with a piece of tissue for too long, will burn throughand perforate the tissue. In many applications, it has proven difficultto balance leaving an ablating tip in position on a piece of tissue fora sufficient time to allow the tissue to be ablated but not leave it inplace for a length of time to burn through and thereby perforate thetissue.

Another problem with prior art ablation devices is that if the ablatingtips are left in contact with the tissue too long, the tip “sticks” tothe tissue being ablated. In removing the tip, large portions of tissueare often removed attached to the tip. This is not only a result to beavoided because of the tissue damage, but it is time consuming andirritating to the physician. These are clearly problems to be avoided.

SUMMARY OF THE INVENTION

In view of the foregoing considerations, the present invention isdirected to an improved electrocautery instrument.

In accordance with one aspect of the invention, the electrocauteryelectrode/tip is implemented with a hollow, conductive tube terminatingat its distal end in a ball point type tip. Conductive fluid is appliedto the proximal end of the hollow electrode/tip, and expelled from thedistal end thereof during electrocautery. The ball point distal tipallows the distal tip to be directly applied to the tissue and “rolled”or slid along the tissue. This allows the distal tip to be moved acrossthe tissue without dragging or snagging on the tissue. In addition, theconductive fluid expelled from the distal tip further lubricates thedistal tip as it moves across the tissue.

In accordance with another aspect of the invention, the conductive fluidemanating from the electrode/tip conducts the RF electrocautery energyaway from the distal tip so that it is primarily the fluid, rather thanthe distal tip that actually accomplishes the cauterizing of tissue.That is, the fluid serves as a “virtual” electrocautery electrode. Sinceit is the fluid, rather than the distal tip that cauterizes, coagulatesand abates, no burns or perforations are made to the tissue, reducingthe amount of debris at the site of ablation. Also, the flow of fluidthrough the electrode/tip tends to keep the distal tip clean and cool.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the present invention may perhaps bebest appreciated with reference to a detailed description of a specificembodiment of the invention, when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a perspective view of an electrocautery instrument inaccordance with one embodiment of the invention.

FIG. 2 is a perspective view of the invention separated from the handle.

FIG. 3 is an enlarged perspective view of the distal end of theelectrocautery device of FIG. 1 showing the electrode/tip.

FIG. 4 is a cross-sectional view of the electrode/tip of the device ofFIGS. 1, 2 and 3.

FIG. 5 is a cross-sectional view of another embodiment of electrode/tipof the invention.

FIG. 6A is a cross-sectional view of another embodiment of electrode/tipof the invention.

FIG. 6B is a cross-sectional view of yet another embodiment ofelectrode/tip of the invention.

DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT OF THE INVENTION

Referring to FIG. 1, there is shown a perspective view of afluid-assisted electrocautery device 10 in accordance with oneembodiment of the invention. Electrocautery device 10 comprises a handle12 and an electrocautery electrode/tip 14. Handle 12 is preferably madeof a sterilizable, rigid, and non-conductive material, such as nylon orthe like. Electrode/tip 14 is attached to handle 12.

In accordance with one aspect of the invention, electrode/tip 14 ispreferably implemented using a hollow cylindrical tube 16 with a “ballpoint” at its distal end, as shown in the greatly enlarged perspectiveand cross-sectional views of FIGS. 3 and 4, respectively. As can beseen, a ball 18 is retained in a cavity formed by crimping metal tube 16around ball 18. Both ball 18 and tube 16 are preferably made of anelectrically conductive metal such as stainless steel. Tube 16 iscrimped both proximal and distal to ball 18 at 20 and 22, respectively.

Ball 18 may have any diameter but balls 18 having diameters of fromabout 1 to about 5 mm have been found to be particularly effective forablating. Tube 16 must have a diameter corresponding to the diameter ofball 18 as explained herein. Consequently, tube 16 preferably has aninternal diameter, particularly at its distal end, of from about 1 toabout 5 mm.

Crimping may be accomplished by a number of techniques including but notlimited to placing a series of “crimps” 24 around the periphery of tube16 that are directed toward the interior 26 of tube 16. In addition, thedistal end 28 of tube 16 is “crimped” by rounding it toward the interior26 of tube 16. In this way, ball 18 is retained between the “crimps” 24and the rounded distal end 28. Crimping should be done so that a portionof ball 18 extends distally beyond distal end 28.

Tube 16 preferably has in interior 26 diameter slightly larger than thediameter of ball 18. In any case, after crimping as described above, theportion of tube 16 surrounding ball 18 should have a slightly largerinternal diameter than ball 18. This allows ball 18 to freely rotatebetween crimps 24 and distal end 28 and still be retained atelectrode/tip 14.

An electrical insulator 30 preferably surrounds tube 16 alongsubstantially its entire length, terminating a short distance fromdistal end 28. Insulator 30 prevents accidental cautery from takingplace at locations other than electrode/tip 14 if tube 16 shouldinadvertently contact patient tissue during a procedure.

Two connections are made to electrocautery device 10. One terminal(e.g., positive) of a radio-frequency (RF) generator (not shown inFIG. 1) is electrically coupled to electrode/tip 14 via a wire 32attached to tube 16. Contact between ball 18 and tube 16, as will bedescribed in more detail hereafter, provides electrical potential toball 18.

A source of fluid to be expelled from electrode/tip 14 is coupled totube 16 via a flexible input line 34. Input line 34 is preferably a tubeor hose. Conductive fluid is provided under pressure through tube 16 tothe electrode/tip 14. The conductive fluid is introduced to tube 16, asshown in FIG. 2, through input line 34 that is connected to a fluidinlet port 36 on tube 16. Conductive fluid passes from inlet line 34through fluid inlet port 36 into tube 16 and is communicated along thelength of tube 16 to electrode/tip 14 to be expelled from the distal endthereof This creates a so-called “virtual electrode” for performingelectrocautery.

The infusion of conductive fluid simultaneously with the application ofRF energy is discussed in further detail in: U.S. patent applicationSer. No. 08/113,441 entitled “Method and Apparatus for R-F Ablation,”filed on Aug. 27, 1993 in the name of Peter M. J. Mulier and Michael F.Hoey, in U.S. patent application Ser. No. 08/303,246, entitled “Methodand Apparatus for RF Ablation,” filed on Sep. 8, 1994 in the name ofPeter M. J. Mulier; in U.S. patent application Ser. No. 08/302,304entitled “Method and Apparatus for RF Ablation,” filed in the name ofPeter M. J. Mulier and Michael F. Hoey on Sep. 8, 1994 and in U.S.patent application Ser. No. 08/393,082 entitled “Fluid AssistedElectrocautery Device”, filed in the name of Peter M. J. Mulier andMichael F. Hoey on Feb. 22, 1995. The foregoing '441, '246, '304 and'082 applications hereinafter collectively referred to as “the RFablation applications”) are each commonly assigned to the assignee ofthe present invention, and incorporated by reference herein in theirrespective entireties.

As described in the RF ablation patent applications, the infusion ofconductive fluid into the area of application of RF energy creates a“virtual electrode,” the size and shape of which can be controllablymodified, and which can be rendered more or less conductive, therebymodifying the spread of RF energy. By varying such factors as the RFenergy and duration, the rate of infusion of conductive liquid, and theconductivity of the infused solution, the size, shape, and intensity ofthe “virtual electrode”—i.e., the intensity of thermal production in thearea, can be controlled. In the case of the electrocautery device inaccordance with the present invention, application of the conductivesolution during the application of RF energy further assists bypreventing overheating of the electrode/tip, extending the point atwhich burning or charring of tissue would otherwise normally occur. Toenhance this effect, it is contemplated that the solution being infusedmay first be cooled.

Conductive solutions believed to be suitable for establishing thevirtual electrode include saline, saturated saline, and Ringer'ssolution, among others. Regarding the source of conductive fluid, it iscontemplated that a conventional pump may be coupled to input line 34.Alternatively, it is contemplated that a small, pre-pressurized canisterof conductive solution may be used, such that no pump is required. Inone embodiment, handle 12 may be configured to receive such apressurized canister therein, eliminating the need for input line 34.

In addition, a dye may be mixed with the conductive fluid to make thefluid more visible during the procedure using the device 10. Examples ofsuch a dye include, but are not limited to methylene blue.

It is desirable to provide the conductive fluid to electrode/tip 14under pressure that is controlled. In particular, it is important not tohave a flow rate that allows conductive fluid to flow excessively out ofthe distal end 28 of electrode/tip 14. Excessive fluid flow has beenshown to spread the electrical current density over a large area of thetissue thereby minimizing, and in some cases preventing, the ablationeffect.

In use, electrical potential is applied to tube 16 from aradio-frequency (RF) generator as described above. Since tube 16 is madeof an electrically conductive metal, the entire tube 16 will be at anelectrical potential determined by the radio-frequency (RF) generator.Conductive fluid is supplied under pressure to the device 10 so that theconductive fluid is expelled from electrode/tip 14 around ball 18.

The user of electrocautery device 10 places electrode/tip 14 at an areato ablate and moves the electrode/tip 14 across the tissue by ball 18contacting the tissue. Ball 18 may either roll or be slid across thetissue. The fluid expelled from the distal end 28 lubricates the tissueand facilitates the movement of ball 18 across the tissue regardless ofwhether ball 18 rolls or slides across the tissue.

In vitro experiments have shown the following: The larger the diameterof ball 18, the wider and deeper the ablation “track” created on thetissue; Moving the electrode/tip 14 slowly across the tissue createsdeeper lesions than if electrode/tip 14 is moved quickly; and the flowrate of conductive fluid through device 10 and out of electrode/tip 14should be adequate to wet and lubricate the surface of the tissue butshould not be so high as to spread across the tissue and spread theelectrical current density necessary to perform the ablation. Asexamples of desirable flow rates of conductive fluid through the device10, with a radio-frequency (RF) generator at 50 Watts, a flow rate ofabout between 0.5 and 2 cc/minute was shown to be adequate and with aradio-frequency (RF) generator at 25 Watts, a flow rate of about between1 and 2 cc/minute was shown to be adequate. Other flow rates in thesepower ranges or these or different flow rates for other power settingsmay also be used as will be clear with practice using the invention. Theexamples given above being given for the purpose of illustration and arenot intended to be limiting.

The device 10 may be particularly used in connection with the so called“maze” procedure described above to ablate an area of the heart tointerrupt all the potential re-entry circuit patterns that could occurin the atria and cause atrial fibrillation. The device 10 could also beused advantageously to remove hemorrhoids or varicose veins or stopesophageal bleeding to name but a few possible uses. The device removesthe risk of perforation commonly found with other types of cautery, iseasy to “write” with and allows deep and wide penetration andsubsequently ablation.

Because of its similarity to a ball point pen, the invention provides anelectrocautery device 10 that is easy to “write” with. That is, it iseasy to move the distal elected/tip 14 across the tissue to be ablatedbecause the ball 18 rolls across the tissue. In addition, by expellingfluid from electrode/tip 14, ball 18 also slides across the tissue beingablated.

Although in the embodiment of FIG. 1, wire 32 and input line 34 aredepicted separately, it is contemplated that these connections to device10 may be consolidated into a single line having a fluid-conductinglumen therein for input of conductive solution alongside an insulatedelectrical conductor.

Various alternate configurations of electrode/tip 14 are alsocontemplated. In one embodiment shown in FIG. 5, ball 18 is enclosedwithin tube 16 at the distal end 28 of tube 16. However, instead ofhaving crimps 24 proximal to ball 18, a block 38 is placed proximal toball 18 within tube 16. Block 38 preferably has a central lumen 40exiting from its proximal to its distal end to allow fluid in theinterior of tube 16 to pass to ball 18 where it ma be expelled fromdistal end 28. In all other ways, this embodiment is identical to thepreferred embodiment described above.

Ball 18 may also be made of a porous, electrically conductive material.In this embodiment, the porous nature of ball 18 allows fluid to notonly pass around ball 18 to be expelled from distal end 28, but alsoallows fluid to pass through ball 18 to be expelled.

In another alternate embodiment, ball 18 is replaced with anon-spherical contact element as shown in FIG. 6A, such as anelectrically conductive elongated plug 42 shown in FIG. 6B. In thisembodiment, the plug is made of an electrically conductive porousmaterial retained at the distal end 28 of tube 16 so that fluid can passthrough the plug to be expelled from the distal end 28. The plug may beretained by any means described above including, but not limited to,crimps or a rounded distal end. Because the plug is not spherical, theplug can not roll as it is moved in contact across the tissue to beablated. Instead, the plug will slide across the tissue.

Although the invention has been described in connection with using aconductive fluid to create a virtual electrode for electrode/tip 14, itis clear that many of the advantages of the invention such as the smoothflow of electrode/tip 14 will also be produced with the conductive fluidreplaced with non-conducting fluid such as pure water. Therefore, it isalso within the scope of the invention to include the use of anon-conducting fluid.

In addition, if desired, a suction tube may be added to the device 10 toallow smoke or excess fluid to be removed from the surgical field. Sucha suction tube is described in the '082 application described above, theteachings of which have been incorporated by reference herein.

Further, tube 16 may be made of an electrically insulating materialexcept for a portion at its distal end that comes in contact with ball14. This portion of tube 16 that comes in contact with ball 14 should beelectrically conducing. In this embodiment, wire 24 extends to thiselectrically conducting portion of tube 16.

From the foregoing detailed description of a specific embodiment of theinvention, it should be apparent that a method and apparatus forperforming fluid-assisted electrocautery of body tissue has beendisclosed, wherein fluid delivered out of a hollow electrocauteryelectrode/tip creates a virtual electrode which incises and cauterizesthe tissue.

Although a specific embodiment of the invention has been describedherein, this has been done solely for the purposes of illustratingvarious aspects of the invention, and is not intended to be limitingwith respect to the scope of the invention. It is contemplated thatvarious substitutions, alterations, and/or modifications, including butnot limited to those specifically discussed herein, may be made to thedisclosed embodiment without departing from the spirit and scope of theinvention as defined in the appended claims, which follow.

1. (canceled)
 2. (canceled)
 3. A pen-type electrosurgical instrument tosimultaneously provide radio-frequency energy and a fluid to treattissue during surgery, the instrument comprising: a handle; a tubedistal to the handle, the tube having a distal end; an electrode tipretained by the tube, at least a portion of the electrode tip distal tothe distal end of the tube, the portion of the electrode tip distal tothe distal end of the tube comprising a spherical surface; a lumenconnectable to a source of fluid; at least one fluid exit in fluidcommunication with the lumen, the fluid exit adjacent the electrode tip;and a terminal in electrical communication with the electrode tip, theterminal connectable to a source of radio-frequency energy.
 4. Theinstrument of claim 3, wherein the fluid exit is at the distal end ofthe tube.
 5. The instrument of claim 3, wherein the fluid exit isbetween the electrode tip and the tube.
 6. The instrument of claim 3,wherein the fluid exit is defined by a surface portion of the electrodetip.
 7. The instrument of claim 3, wherein the fluid exit is defined bya surface portion of the tube.
 8. The instrument of claim 3, wherein thefluid exit is adjacent to the spherical surface.
 9. The instrument ofclaim 3, wherein the spherical surface of the electrode tip is providedby a surface portion of a ball.
 10. The instrument of claim 9, whereinthe ball has a diameter in the range of about 1 mm to 5 mm.
 11. Theinstrument of claim 3, wherein the spherical surface has a radius in therange of about 0.5 mm to 2.5 mm.
 12. The instrument of claim 3, whereinthe electrode tip comprises a ball.
 13. The instrument of claim 3,wherein the electrode tip comprises a metal.
 14. The instrument of claim3, wherein the electrode tip comprises an electrically conductivematerial.
 15. The instrument of claim 3, wherein the electrode tipcomprises stainless steel.
 16. The instrument of claim 3, wherein theelectrode tip is porous.
 17. The instrument of claim 3, wherein theelectrode tip is non-porous.
 18. The instrument of claim 3, wherein theelectrode tip is configured to roll along a tissue surface.
 19. Theinstrument of claim 3, wherein the electrode tip is configured to slidealong a tissue surface.
 20. The instrument of claim 3, wherein a portionof the electrode tip is in the tube.
 21. The instrument of claim 3,wherein a portion of the electrode tip is enclosed by the tube.
 22. Theinstrument of claim 3, wherein at least a distal portion of the tube iselectrically conductive.
 23. The instrument of claim 3, wherein the tubecomprises metal.
 24. The instrument of claim 3, wherein the tubecomprises stainless steel.
 25. The instrument of claim 3, wherein thetube is hollow.
 26. The instrument of claim 3, wherein the tube iscylindrical.
 27. The instrument of claim 3, wherein at least a portionof the tube is electrically insulated.
 28. The instrument of claim 3,wherein the tube comprises an electrically insulative material.
 29. Theinstrument of claim 3, wherein the lumen is at least in a portion of thetube proximal to the distal end of the tube.
 30. The instrument of claim3, wherein the handle is configured to facilitate a user holding theinstrument like a pen.
 31. The instrument of claim 3, wherein the handleis configured to facilitate a user manipulating the instrument like apen.
 32. The instrument of claim 3, wherein the tube is configured tomanipulate the electrode tip like a pen tip in response to amanipulation of the handle.
 33. The instrument of claim 3, wherein thehandle and the tube are configured to facilitate a user manipulating theelectrode tip like a pen tip.
 34. The instrument of claim 3, wherein aportion of the lumen is provided by the tube.
 35. The instrument ofclaim 3, wherein the lumen is connectable to the source of fluid with afluid input line.
 36. The instrument of claim 3, wherein: a portion ofthe lumen is provided by a fluid input line; and electricalcommunication between the terminal and the electrode tip is provided bya wire.
 37. The instrument of claim 36, wherein a portion of the fluidinput line and a portion of the wire are contained in the handle.